In 17th century France, young d'Artagnan wants to join the King's Musketeers, but instead befriends three legendary musketeers — Athos, Porthos, and Aramis — and together, they become embroiled in the political intrigue surrounding King Louis XIII and his adversaries, particularly the powerful Cardinal Richelieu.

Barry Brandon, a criminal lawyer, visits the night club of Denny Larkin, his primary client, with Betty Walker, a spoiled society girl. The police raid the club and Brandon pleads that the whole group is guilty, just to get even with Larkin for a rebuke. On the same night in court, Madge Carter is on trial for disorderly conduct, and Brandon volunteers to defend her, and proves the case against her if a frame-up. Finding that she is penniless, Brandon hires her as his secretary, and falls in love with her. Brandon is appointed district attorney and has ambitions of becoming the state governor. Having dinner at Betty's home, she maneuvers him, while he is drunk, into marrying her. Later, Madge is a witness when Larkin shoots down a fellow gangster. By threatening Brandon's life, he forces her to commit perjury at his trial, and say he fired in self-defense. Brandon, the prosecuting attorney (who has had his marriage to Betty annulled) knows she is lying but doesn't know why.

Private eye Edward Mercer travels to Venice to locate a man due a reward for his aid in the war. Shortly after arriving, he becomes the prime suspect in the murder of his local contact. In his quest to clear his name, Mercer uncovers a conspiracy. Even the local magistrate seems to be working against him, and Mercer begins to suspect the man he came to find is behind it all.